Beam shot position correction coefficient computation/updating technique for ultrafine pattern fabrication using variable shaped beam lithography

Abstract

A charged-particle beam lithography apparatus includes a charged-particle beam irradiation unit, a deflector which deflects the charged particle beam, a stage which disposes thereon a workpiece for pattern writing and a plurality of marks being regularly laid out in an entire area substantially equal to a pattern writing region of the workpiece, a measurement unit for measuring positions of the marks on the stage through scanning of the charged-particle beam by the deflector, a coefficient calculation unit which uses an approximation equation for correction of a position deviation occurring due to a hardware configuration of the apparatus to perform the fitting of a position deviation amount of each mark by a coordinate system of the apparatus to thereby calculate more than one coefficient of the fitting-applied approximation equation, and a storage unit which performs overwrite-storing whenever the coefficient calculation unit calculates the coefficient.

1. A charged particle beam lithography apparatus comprising:
 an irradiation unit operative to irradiate a charged particle beam; 
 a deflector operative to deflect the charged particle beam; 
 a stage disposing thereon a workpiece for pattern writing and a substrate with a plurality of marks being regularly laid out in an entire area substantially equal to a pattern writing region of the workpiece, said substrate being disposed at a position on the stage different from a position of said workpiece on the stage; 
 a measurement unit operative to measure positions of the plurality of marks on said stage through scanning of the charged particle beam by said deflector; 
 a coefficient calculation unit operative to use an equation of approximation for correction of a position deviation occurring due to a hardware configuration of the apparatus to perform fitting of a deviation amount of the position of each mark by a coordinate system of said apparatus to thereby calculate more than one coefficient of the approximation equation with the fitting applied thereto; and 
 a storage unit operative to perform overwrite storing whenever said coefficient calculation unit calculates said coefficient. 
 
     
     
       2. The apparatus according to  claim 1 , wherein said substrate has a film formed to have on its surface a pattern of projections corresponding to said marks being formed thereon. 
     
     
       3. A charged particle beam lithography apparatus comprising:
 an irradiation unit operative to irradiate a charged particle beam; 
 a deflector operative to deflect the charged particle beam; 
 a stage disposing thereon a workpiece for pattern writing and a plurality of marks being regularly laid out in an entire area substantially equal to a pattern writing region of the workpiece and disposed at a position on the stage different from a position of said workpiece on the stage, said plurality of marks being preformed on a surface of said stage; 
 a measurement unit operative to measure positions of the plurality of marks on said stage through scanning of the charged particle beam by said deflector; 
 a coefficient calculation unit operative to use an equation of approximation for correction of a position deviation occurring due to a hardware configuration of the apparatus to perform fitting of a deviation amount of the position of each mark by a coordinate system of said apparatus to thereby calculate more than one coefficient of the approximation equation with the fitting applied thereto; and 
 a storage unit operative to perform overwrite storing whenever said coefficient calculation unit calculates said coefficient, 
 wherein said deflector deflects the charged particle bean at a position on said workpiece corrected by using said coefficient calculated by using said plurality of marks disposed at the position on the stage different from that of said workpiece. 
 
     
     
       4. A position correction coefficient calculation method of a charged particle beam lithography apparatus for calculating more than one coefficient of an approximation equation used to correct a position deviation occurring due to a hardware configuration of the lithography apparatus, said method comprising:
 scanning using a charged particle beam a plurality of marks regularly disposed in an entire area equivalent to a pattern writing region of a workpiece for pattern writing on a stage, said plurality of marks being disposed at a position on the stage different from a position of said workpiece on the stage and being preformed on a surface of said stage; and 
 performing fitting of a position deviation amount of each scanned mark by a coordinate system of the lithography apparatus to thereby calculate more than one coefficient of the approximation equation with the fitting applied thereto and then outputting the coefficient calculated for correcting a position on said workpiece. 
 
     
     
       5. A position correction coefficient updating method of a charged particle beam lithography apparatus for updating more than one coefficient of an approximation equation being stored in a storage device, the coefficient being for correction of a position deviation occurrable due to a hardware configuration of the lithography apparatus, said method comprising:
 scanning using a charged particle beam a plurality of marks being regularly disposed in an entire area corresponding to a pattern writing region of a workpiece for pattern writing on a stage, said plurality of marks being disposed at a position on the stage different from a position of said workpiece on the stage and being preformed on a surface of said stage; 
 performing fitting of a position deviation amount of each scanned mark by a coordinate system of the lithography apparatus to thereby calculate more than one coefficient of the approximation equation with the fitting applied thereto; and 
 overwriting the calculated coefficient on a previously defined coefficient being stored in said storage device for correcting a position on said workpiece. 
 
     
     
       6. The method according to  claim 5 , further comprising: periodically updating said coefficient once per time period shorter than six (6) months.